Diabetes treatment: not just insulin?

Lowering glucose levels is a task with several solutions
Anastasia Kazantseva, STRF.ru

Glucose is the main source of energy for all our cells, and it is not surprising that in the course of evolution, effective systems have been formed to maintain its constant level in the blood. Simplistically, this scheme looks like this: glucose received from food is stored in the liver in the form of an insoluble polymer – glycogen. In the event that the level of glucose in the blood decreases, the hormone glucagon acts on the liver, under the influence of which part of the glucose reserves passes into the blood. If the glucose level rises, then another hormone, insulin, activates the consumption of glucose by cells, including its accumulation in the liver in the form of glycogen.

Type I diabetes mellitus is a condition in which insufficient insulin is produced and there is no way to effectively reduce blood glucose levels. Most of the severe complications caused by diabetes are not even due to the fact that cells do not absorb glucose and starve, but to the fact that a high concentration of sugar in the blood leads to pathological changes in the walls of blood vessels and, as a consequence, to a violation of blood supply to various organs.

All existing methods of controlling the development of diabetes, as well as all potential methods of its final cure, are reduced to increasing the level of insulin. However, in the February issue of Diabetes magazine, an article was published (Young Lee et al., Glucagon Receptor Knockout Prevents Insulin-Deficient Type 1 Diabetes in Mice), the authors of which suggest focusing on the second participant of this system – glucagon. If this hormone does not contribute too intensively to the release of glucose from the liver into the blood, then the problem of increasing sugar levels will disappear by itself.

"We all used to think that insulin is an all–powerful hormone, without which life is impossible. But this is not quite true," Roger Unger, head of the study, quotes the website of the University of Texas Medical Center (UT Southwestern researchers discover potential 'cure' for type 1 diabetes). – If diabetes is defined as a violation of glucose metabolism, then our method of therapy can allow us to come very close to the "cure" of diabetes."

The scientists worked with genetically modified mice unable to synthesize glucagon receptors. Normally, such receptors are located on the surface of liver cells, perceive a signal from the hormone and trigger the process of releasing glucose stored in the liver.

Mice were subjected to a glucose tolerance test. This test, often used to diagnose diabetes, consists in the fact that the subject receives a large dose of glucose, and then the researchers assess how quickly the blood glucose level drops to normal values.

Animals whose insulin production was not disrupted tolerated the test well, regardless of whether their glucagon receptors worked. But, after the mice were destroyed by the beta cells of the pancreas that produce insulin, and again subjected to a glucose tolerance test, the difference between the two groups was noticeable. If a mouse incapable of producing insulin is also deprived of glucagon receptors, it demonstrates a normal rate of decrease in blood glucose levels. At the same time, a mouse that does not have insulin, but has glucagon and functional receptors for it, is unable to effectively reduce glucose levels.

During the six weeks of the experiment, mice with functional glucagon receptors and impaired insulin production developed real diabetes mellitus – with hyperglycemia, hyperketonemia, polyuria and all other symptoms. At the same time, animals kept on the same diet, deprived of both insulin and glucagon receptors, remained healthy.

"Our study shows that if you don't have glucagon, it becomes unimportant whether you have insulin," says Anger. "This does not mean that everyone will be able to do without insulin: it is important for the normal growth of children. But in adulthood, as far as glucose regulation is concerned, insulin is needed precisely in order to control glucagon."

Researchers believe that the development of drugs that block glucagon or its receptors in the human body can dramatically reduce patients' need for insulin and prevent the development of diabetes symptoms.

Portal "Eternal youth" http://vechnayamolodost.ru
31.01.2011